Process and power system utilizing potential of ocean thermal energy conversion

ABSTRACT

Ocean Thermal Energy Conversion (OTEC) systems and methods utilizing the systems are disclosed for producing a useable form of energy utilizing warm surface seawater and cold seawater from depths up to 2 miles below the surface and utilizing a multi-component working fluid. The systems and methods are designed to maximize energy conversion per unit of cold seawater, the limited resource, achieving relative net outputs compared to a Rankine cycle using a single component fluid by at least 20% and even as high as about 55%.

RELATED APPLICATIONS

The present application is a continuation-in-part of U.S. patentapplication Ser. No. 13/188,063 filed 21 Jul. 2011 (Jul. 21, 2011)(21,Jul. 2011).

BACKGROUND OF THE INVENTION

1. Field of the Invention

Embodiments of the present invention relates to systems and methodutilizing with heat sources having very low temperatures.

More specifically, embodiments of the present invention relates tosystems and method utilizing with heat sources having very lowtemperatures, where the very low temperature streams are derived fromwarm ocean surface water and the systems and methods derive energypotential for Ocean Thermal Energy Conversion (OTEC.)

2. Description of the Related Art

The energy potential of OTEC is the temperature difference of warmsurface water and cooler water from deep below the surface. Such anenergy source is practically limitless. Warm seawater from the oceansurface is readily available. On the other hand, cooler water from thedeep ocean must be pumped to the surface and thus obtaining this coolerwater comes with technological effort and costs.

Therefore, a key criterion for effectiveness of an OTEC power system isthe specific output of energy per unit of flow of the cooler water,rather than the warm surface water.

Thus, there is a need in the art for efficient and effective systems andmethods for extracting energy from ocean sources for OTEC.

SUMMARY OF THE INVENTION

Embodiments of the present invention provide systems for generatingelectrical and/or mechanical energy, where a rich solution stream and anintermediate solution stream derived from a multi-component workingfluid are partially vaporized by warm seawater and a rich solutionstream and an intermediate solution stream are fully condensed by coldseawater. The systems include a vessel or a floating platform, where atemperature differential between the warm seawater and the cold seawateris modest—between about 15° C. and about 30° C. The systems includevessel or floating platform on which is mounted and operated a thermalenergy conversion subsystem, a warm seawater supply subsystem, a warmseawater discharge subsystem, a cold seawater supply subsystem and acold seawater discharge subsystem. The thermal energy conversionsubsystems comprise a turbine or energy converting unit, a condensingunit, two preheating units, two vaporizing units, and two separatingunits. The thermal energy conversion system comprises also includesdividing valves, combining valves, throttle control valves, and pumpsand piping to interconnect the units and to produce an operableconfiguration. The thermal energy conversion subsystem uses the warmseawater to partially vaporize a rich solution stream and anintermediate solution stream. The thermal energy conversion subsystemthen separates the partially vaporized rich solution into a rich vaporstream that is forwarded to the turbine unit, where a portion of itsthermal energy is converted into a useable form of energy (electricaland/or mechanical). The warm seawater supply subsystem includes acollector for collecting warm seawater from the surface of the ocean/seaand pipes to direct the warm seawater to the thermal energy conversionsystem, while the warm seawater discharge subsystem includes a spentwarm seawater discharge and optionally one or more processing units toprocess the water in case of contamination. The cold seawater supplysubsystem includes a collector for collecting cold seawater from a depthbetween about 0.5 and 1.5 miles below the surface of the ocean/sea andpipes to direct the cold seawater to the thermal energy conversionsystem, while the cold seawater discharge subsystem includes a spentcold seawater discharge and optionally one or more processing units toprocess the water in case of contamination.

Embodiments of the present invention provide thermal energy conversionsubsystems comprising a turbine or energy converting unit, a condensingunit, two preheating units, two vaporizing units, and two separatingunits. The thermal energy conversion system comprises also includesdividing valves, combining valves, throttle control valves, and pumpsand piping to interconnect the units and to produce an operableconfiguration. The thermal energy conversion subsystem uses the warmseawater to partially vaporize a rich solution stream and anintermediate solution stream. The thermal energy conversion subsystemthen separates the partially vaporized rich solution into a rich vaporstream that is forwarded to the turbine unit, where a portion of itsthermal energy is converted into a useable form of energy (electricaland/or mechanical).

Embodiments of the present invention provide methods for producingelectrical and/or mechanical energy from a temperature different betweenwarm surface seawater and cold seawater collected at depths up to 2miles below the surface of an ocean or sea. The methods include passinga first rich vapor stream, which may be pressure adjusted in a secondthrottle control valve if needed, through a turbine unit, where aportion of thermal energy in the first rich vapor stream is converted toa useable form of energy to produce a spent rich solution stream. Thespent rich solution stream is then combined with a cooled second leanliquid stream, which may be pressure adjusted in a third throttlecontrol valve if needed, to form an intermediate solution stream, wherethe intermediate solution stream is leaner than the rich solutionstream. The intermediate solution stream is then fully condensed in afirst condenser to form a fully condensed intermediate solution streamutilizing a cold seawater stream. The fully condensed intermediatesolution stream is pressurized in a second pump to a higher pressure toform a higher pressure, fully condensed intermediate stream, which isthen divided into two substreams. The first higher pressure, fullycondensed intermediate substream is combined with a second rich vaporstream to form a rich solution stream. The rich solution stream is thenfully condensed in a second condenser to form a fully condensed richsolution stream utilizing a warmed cold seawater stream. The fullycondensed rich solution stream is then pumped in a first pump to ahigher pressure and forwarded to a preheater, where the higher pressure,fully condensed rich solution stream is preheated utilizing a firstcooled warm seawater substream. The preheated higher pressure, richsolution stream is then partially vaporized in a first partial vaporizerunit to from a partially vaporized, rich solution stream and a cooledwarm seawater stream, which is divided into the first cooled warmseawater substream and a second cooled warm seawater substream. Thepartially vaporized, rich solution stream is then forwarded to a firstseparator to form the first rich vapor stream and a first lean liquidstream. Meanwhile, the second higher pressure, fully condensedintermediate substream is preheated utilizing the a second lean liquidstream to form a preheated, second higher pressure, intermediatesubstream and the cooled second lean liquid stream. The preheated,second higher pressure, intermediate substream is then partiallyvaporized in a second partial vaporizer unit to form a partiallyvaporized, second higher pressure, intermediate substream utilizing thesecond cooled warm seawater substream. The partially vaporized, secondhigher pressure, intermediate substream is then combined with the firstlean liquid stream, which may be pressure adjusted by a first throttlecontrol valve, if needed, to form a lean solution stream. The leansolution stream is then forwarded to a second separator to form thesecond rich vapor stream and the second lean liquid stream. The systemis closed with respect to the multi-component working fluid.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention can be better understood with reference to the followingdetailed description together with the appended illustrative drawings inwhich like elements are numbered the same:

FIG. 1 depicts an embodiment of a ocean based system of this invention,including a floating vessel, warm seawater intake and outlet, coldseawater intake and outlet and a thermal energy conversion subsystem.

FIG. 2 depicts an embodiment of the thermal energy conversion subsystemof FIG. 1.

FIG. 3 depicts an embodiment of the thermal energy conversion subsystemof FIG. 1.

FIG. 4 depicts an embodiment of the thermal energy conversion subsystemof FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

The inventor has found that systems and methods can be implemented forderiving useable energy from oceans using very low temperature surfaceocean water and cool deep ocean water. The inventor has found thatcompared to applicable prior art system, the present invention providesa substantial increase in power output per unit of flow rate of coolingwater and a substantial reduction in the use of warm seawater per unitof power generated. The inventor has found that the calculated netoutput of the present invention using a multi-component fluid comprisingammonia and water is improved relative to a Rankine cycle using pureammonia by at least about 20%. In certain embodiments, the improvementin net output is at least about 25%. In other embodiments, theimprovement in net output is at least about 30%. In other embodiments,the improvement in net output is at least about 35%. In otherembodiments, the improvement in net output is at least about 40%. Inother embodiments, the improvement in net output is at least about 45%.In other embodiments, the improvement in net output is at least about50%. In other embodiments, the improvement in net output is at leastabout 55%.

Embodiments of the present system include a vessel or a floatingplatform. The vessel includes a thermal energy conversion subsystem, awarm seawater supply subsystem, a warm seawater discharge subsystem, acold seawater supply subsystem and a cold seawater discharge subsystem.The thermal energy conversion subsystem comprises a turbine or energyconverting unit, a condensing unit, two preheating units, two vaporizingunits, and two separating units. The thermal energy conversion systemcomprises also includes dividing valves, combining valves, throttlecontrol valves, and pumps and piping to interconnect the units and toproduce an operable configuration. The warm seawater supply subsystemincludes a collector for collecting warm seawater from the surface ofthe ocean/sea and pipes to direct the warm seawater to the thermalenergy conversion system, while the warm seawater discharge subsystemincludes a spent warm seawater discharge and optionally one or moreprocessing units to process the water in case of contamination. The coldseawater supply subsystem includes a collector for collecting coldseawater from a depth between about 0.5 and 1.5 miles below the surfaceof the ocean/sea and pipes to direct the cold seawater to the thermalenergy conversion system, while the cold seawater discharge subsystemincludes a spent cold seawater discharge and optionally one or moreprocessing units to process the water in case of contamination.

Embodiments of the present system include thermal energy conversionsubsystems comprising a turbine or energy converting unit, twocondensing unit, two preheating units, two partial vaporizing units, andtwo separating units, where the systems utilize warm seawater stream topartially vaporize streams having different compositions of amulti-component working fluid and cold seawater to fully condensestreams having different compositions of a multi-component workingfluid. The thermal energy conversion system also comprises dividingvalves, combining valves, throttle control valves, and pumps and pipingto interconnect the units, where the valves, pumps and piping produce anoperable configuration.

Embodiments of the present method include collecting warm seawater at ornear the surface of an ocean or a sea, and supplying the collected warmseawater to the thermal energy conversion subsystem. In the thermalenergy conversion subsystem, the warm seawater stream is pumped to adesired higher pressure. The higher pressure warm seawater is then usedto preheat and partially vaporize a higher pressure, rich solutionstream and a higher pressure, intermediate solution stream in thepreheating and vaporizing units. The spent warm stream is thendischarged into the ocean/sea via the warm seawater discharge subsystem.The partially vaporized, higher pressure, rich solution stream is thenseparated in the first separating unit to form a first lean liquidstream and a first rich vapor stream or energy extraction stream. Thefirst rich vapor stream is then forwarded to the turbine unit, where aportion of its thermal energy is converted into a useable form ofenergy, forming a spent stream. Optionally, the first rich vapor streamis pressure adjusted prior to being forwarded to the turbine unit. Thefirst lean liquid stream and a partially vaporized, higher pressureintermediate solution substream are combined and forwarded to the secondseparator unit forming a second lean liquid and a second rich vaporstream. Optionally, the first lean liquid stream is pressure adjustedprior to being combined with the partially vaporized, higher pressureintermediate solution substream. The second rich vapor stream iscombined with a first fully condensed, higher pressure intermediatesolution substream to form the rich solution stream. The rich solutionstream is then fully condensed in a second condensing unit to form afully condensed, rich solution stream. The fully condensed, richsolution stream is then pumped to a higher pressure to form a fullycondensed, higher pressure, rich solution stream. The fully condensed,higher pressure, rich solution stream is then pre-heated in a firstpreheating unit with heat from a cooled warm seawater substream to forma preheated, higher pressure, rich solution stream, and then partiallyvaporized in a first vaporizing unit with heat from the higher pressure,warm seawater stream to form the partially vaporized, higher pressure,rich solution stream and a cooled warm seawater stream. The cooled warmseawater stream is then divided into a first and second higher pressure,cooled warm seawater substreams. The spent steam and a cooled, secondlean liquid stream are combined to form an intermediate solution stream.Optionally, the cooled, second lean liquid stream is pressure adjustedprior to be combined with the spend stream. The intermediate solutionstream is then condensed in a first condensing unit to form a fullycondensed, intermediate solution stream. The fully condensed,intermediate solution stream is then pressurized to form a higherpressure, fully condensed intermediate solution stream. The higherpressure, fully condensed, intermediate solution stream is then splitinto a first higher pressure, fully condensed, intermediate solutionsubstream and a second higher pressure, fully condensed, intermediatesolution substream. The second higher pressure, fully condensed,intermediate solution substream is preheated by the second lean liquidstream to form a preheated, second higher pressure, intermediatesolution substream and the cooled second lean liquid stream. Thepreheated, second higher pressure, intermediate solution substream isthen partially vaporized in the second vaporizing unit with heat from acooled warm seawater substream to form the partially vaporized, secondhigher pressure, intermediate solution substream and a first spend warmseawater stream. The system is closed with respect to themulti-component working fluid.

The systems also include valves for dividing stream and for mixingstream, throttle control valves for adjusting the pressure of stream andpiping needed to implement the methods of this invention. The heatexchange units can be any heat exchanges presently known or that areinvented to bring two streams into counterflow heat exchange contact onewith the other so that heat can transfer from a higher temperaturestream to a lower temperature stream—heating the lower temperaturestream and cooling the higher temperature stream. The system can be landbased or ocean/sea based depending on access to cold seawater. The termvery low temperature means that the warm seawater stream collected foror near the surface of the ocean/sea is between about 20° C. and about30° C., while the temperature of the cold seawater collected from depthbetween about 0.5 miles to about 1.5 miles is between about 1° C. andabout 10° C. In certain embodiments, the temperature of the warmseawater is between about 21° C. and about 29° C., while the temperatureof the cold seawater is between about 2° C. and about 9° C. In certainembodiments, the temperature of the warm seawater is between about 22°C. and about 28° C., while the temperature of the cold seawater isbetween about 3° C. and about 8° C. In certain embodiments, thetemperature of the warm seawater is between about 21° C. and about 29°C., while the temperature of the cold seawater is between about 4° C.and about 8° C. In certain embodiments, sun light may be used to furtherheat the warm seawater streams so that the temperature of the warmseawater stream may be as high as 85° C.

The working fluids used in the systems and methods of this invention aremulti-component fluids that comprise at least one lower boiling pointcomponent—the lower boiling component—and at least one higher boilingpoint component—the higher boiling component. In certain embodiments,the working fluids comprise an ammonia-water mixture, a mixture of twoor more hydrocarbons, a mixture of two or more freon, a mixture ofhydrocarbons and freon, or the like. In general embodiments, the fluidmay comprise mixtures of any number of components with favorablethermodynamic characteristics and solubility. In other embodiments, thefluid comprises a mixture of water and ammonia. Working fluid streamshaving a high concentration of the lower boiling component are referredto as “rich” working fluid streams and working fluid streams with alower concentration of the lower boiling component are referred to as“lean” working fluid streams.

DETAILED DESCRIPTION OF THE FIGURES

Referring now to FIG. 1, an embodiment of Ocean Thermal EnergyConversion (OTEC) system of this invention, generally 100, is shown toinclude a floating vessel 102 floating on a surface 104 of an ocean orsea 106. Mounted on the vessel 102 is a thermal energy conversionsubsystem 108. The system 100 also includes a warm seawater intakesubsystem 110, shown here as a intake pipe 112 having an end 114disposed on the surface 104 or below the surface 104 to supply warmseawater to the subsystem 108. The system 100 also includes a warmseawater outlet subsystem 116, shown here simply as a pipe 118 having anend 120 disposed above, at, or below the surface 104 of the ocean or sea106. The system 100 also includes a cold seawater intake subsystem 122,shown here as a long pipe 124 having an end 126 disposed at a depth δbetween about 0.5 and about 1.5 miles below the surface 104 or the oceanor sea 106. In certain embodiments, the end 126 is disposed at a depth δbetween about 0.75 and about 1.25 miles below the surface 104. In otherembodiments, the end 126 is disposed at a depth δ between about 0.8 andabout 1 mile below the surface 104. The system 100 also includes a coldseawater outlet subsystem 128, shown here simply as a pipe 130 having anend 132 disposed above, at, or below the surface 104 of the ocean or sea106. The outlet subsystems 116 and 128 may include one or moreprocessing steps to insure that the discharged water include nocontaminants incurred during energy extraction. The system may alsoinclude a solar collection subsystem 134 or other means for heating thewarm seawater stream (exhaust from the vessel's engine exhaust system)to raise the temperature of the warm seawater stream before entering thethermal energy conversion subsystem 108.

Referring now to FIG. 2, an embodiment of an energy conversion subsystem108 of FIG. 1 and method of implementing the subsystem and how itoperates is shown.

A warm seawater stream S40 having parameters as at a point 40 suppliedby the warm seawater intake subsystem 110 from the surface 104 of theocean or sea 106 is pumped by a pump P4, to an elevated pressure to forma higher pressure warm seawater stream S41 having parameters as at apoint 41. The higher pressure warm seawater stream S41 is then passesthrough a third heat exchange unit HE3 in counterflow with a pre-heated,higher pressure, rich solution stream S3 having parameters as at a point3 to form a partially vaporized, higher pressure, rich solution streamS8 having parameters as at a point 8 and a cooled higher pressure warmseawater stream S42 having parameters as at a point 42. The third heatexchange unit HE3 serves as a boiler for the power system's, higherpressure, rich solution stream S3, where the higher pressure warmseawater stream S40 transfers a portion of its thermal energy to thepre-heated higher pressure, rich solution stream S3 in a third heatexchange process 3-8 or 41-42.

The cooled higher pressure warm seawater stream S42 is now divided intotwo cooled higher pressure warm seawater substreams S43 and S45 havingparameters as at points 43 and 45, respectively.

The cooled higher pressure warm seawater stream S43 now passes through asecond heat exchange unit HE2, where it is further cooled, providingheat for preheating of a higher pressure, rich solution stream S2 havingparameters as at a point 2 in a second heat exchange process 2-3 or43-44 as described below to form the spent warm seawater substream S44having parameters as at a point 44 and the pre-heated, rich solutionstream S3.

Meanwhile, the cooled higher pressure warm seawater substream S45 passesthrough a fourth heat exchange unit HE4, where it is further cooled,providing heat for vaporizing an auxiliary rich solution stream S6having parameters as at a point 6 in a second heat exchange process6-5-7 or 45-48-46 as described below to form a vaporized, higherpressure rich solution stream S7 having parameters as at a point 7 and aspent warm seawater substream S46 having parameters as at a point 46.

Thereafter, the spent warm seawater streams S46 and S44 are combined toform a combined spent warm seawater stream S47 having parameters as at apoint 47, which is then process and/or discharged from the subsystem 108via the warm seawater outlet subsystem 116.

A fully condensed rich solution stream S1 having parameters as at apoint 1, corresponding to a state of saturated or slightly subcooledliquid, enters into a first or feed pump P1, where it is pressurized toa higher pressure to form the higher pressure, rich solution stream S2having parameters as the point 2, corresponding to a state of subcooledliquid.

Thereafter, the stream S2 passes through the second heat exchange orpreheater unit HE2, where it is heated in counterflow with the cooledhigher pressure warm seawater substream S43 in the second heat exchangeprocess 43-44 or 2-3 as described above to form the pre-heated richsolution stream S3, corresponding to a state of saturated or slightlysubcooled liquid.

Thereafter, the higher pressure, rich solution stream S3 enters into theboiler or third heat exchange unit HE3, where is further heated incounterflow with the higher pressure warm seawater stream S41 in thethird heat exchange process 41-42 or 3-8 as described above, where thepreheated, higher pressure, rich solution stream S3 is vaporized to formthe partially vaporized, higher pressure, rich solution stream S8 havingparameters as at the point 8, corresponding to a state of vapor-liquidmixture.

The partially vaporized, higher pressure, rich solution stream S8 is nowsent into or forwarded to a first gravity separator SP1, where it isseparated into a saturated rich vapor stream S16 having parameters as ata point 16 and a first lean saturated liquid stream S11 havingparameters as at a point 11.

The saturated rich vapor stream S16 is now sent through an admission orsecond throttle control valve TV2, where its pressure is slightlyreduced to form a reduced pressure vapor stream S17 having parameters asat a point 17. The reduced pressure vapor stream S17 is then sent into aturbine T1, where it is expanded, producing power, forming a spentstream S18 having parameters as at a point 18, corresponding to a stateof wet vapor. A pressure of the spent stream S18 is substantially lowerthan a pressure of the rich solution stream S1 as described above.

The spent stream S18 is now combined with a cooled, pressure adjusted,second lean liquid stream S21 having parameters as at a point 21,forming a vapor-liquid mixed stream S22 having parameters as at a point22. The stream S22 is referred to as an intermediate solution, and issubstantially leaner than the rich solution stream of the stream S1. Thecomposition of the intermediate solution stream S22 allows the streamS22 to be condensed at substantially lower pressure than the pressure ofthe stream S1.

The intermediate solution stream S22 is then fully condensed in alow-pressure condenser or sixth heat exchange unit HE6 in counterflowwith a pressurized cold seawater stream S51 having parameters as at apoint 51 supplied by the cold seawater intake subsystem 122 in a sixthheat exchange process 51-52 or 22-23 as described below. As a result ofthe sixth heat exchange process 51-52 or 22-23, the intermediatesolution stream S22 is converted into a fully condensed intermediatesolution stream S23 having parameters as at a point 23 and thepressurized cold seawater stream S51 is converted into a warmedpressurized cold seawater stream S52 having parameters as at a point 52.The fully condensed intermediate solution stream S23, corresponding to astate of saturated liquid. The concentration of lower boiling component,and correspondingly a pressure of condensed intermediate solution streamS23 is substantially lower than at the rich solution stream S1. As aresult, the rate of expansion in the turbine T1 is increased, with acorresponding increase in power output.

The fully condensed intermediate solution stream S23 is now sent into acirculating or second pump P2, where its pressure is increased to anintermediate pressure, a pressure slightly higher than the pressure ofthe rich solution stream S1 to form a pressurized intermediate solutionstream S24 having parameters as at a point 24. The pressurizedintermediate solution stream S24 corresponds to a state of subcooledliquid.

The pressurized intermediate solution stream S24 is then divided intotwo pressurized intermediate solution substreams S9 and S25, havingparameters as at points 9 and 25.

The pressurized intermediate solution substream S9 is sent into arecuperative preheater or fifth heat exchange unit HE5, where it isheated in counterflow with a second lean liquid stream S20 havingparameters as at a point 20 in a sixth heat exchange process 20-10 or9-6 as described below to form a preheated, pressurized intermediatesolution stream S6 having parameters as at a point 6 and a cooled secondlean liquid stream S10 having parameters as at a point 10. Thepreheated, pressurized intermediate solution stream S6 corresponds to astate of saturated or subcooled liquid.

The pressurized intermediate solution substream S6 is now sent into thefourth heat exchange unit HE4, where it is heated in counterflow by thecooled higher pressure warm seawater stream substream S45 in the fourthheat exchange process 45-48-46 or 6-5-7 as described above. Thepressurized intermediate solution substream S6 is partially vaporized toform a partially vaporized, pressurized intermediate solution substreamS7 having parameters as at point 7. The partially vaporized, pressurizedintermediate solution substream S7 corresponds to a state of avapor-liquid mixture.

At the same time, the first lean saturated liquid stream S11 derivedfrom the first separator SP1 as described above passes through athrottle control valve TV1, where its pressure is reduced to a pressureof the partially vaporized, pressurized intermediate solution substreamS7 to form a pressure adjusted mixed vapor-liquid stream S19 havingparameters as at a point 19. The mixed stream S19 corresponds to a stateof a vapor-liquid mixture.

The streams S7 and S19 are now combined to form a third vapor-liquidmixed stream S14 having parameters as at a point 14.

The third vapor-liquid stream S14 now enters into a second gravityseparator SP2, where it is separated into a very rich saturated vaporstream S15 having parameters as at a point 15 as described herein andthe second lean saturated liquid stream S20 having the parameters as atthe point 20.

The second lean saturated liquid stream S20 is now sent into the fifthheat exchange unit HE5, where it is cooled, providing heat for the fifthheat exchange process 9-6 or 20-10 as described above to form the cooledsecond lean liquid stream S10.

The cooled second lean liquid stream S10 is then sent through a thirdthrottle control valve TV3, where its pressure is reduced to a pressureequal to a pressure of the spent stream S18 to form the cooled, pressureadjusted, second lean liquid stream S21. The cooled, pressure adjusted,second lean liquid stream S21 is then combined with the spent stream S18to form the intermediate solution stream S22 as described above.

Meanwhile, the very rich vapor stream S15 is combined with pressurizedintermediate solution substreams S25 as described above to form a richsolution or base solution stream S26 having parameters as at a point 26,which corresponds to a state of a vapor-liquid mixture.

The rich solution stream S26 is then sent into a condenser or first heatexchange unit HE1, where it is cooled in counterflow by the warmedpressurized cold seawater stream S52 in a first heat exchange process52-53 or 26-1 as described below, is fully condensed forming the fullycondensed rich solution stream S1 as described above.

The cycle is closed.

A cold seawater stream S50, delivered from deep under the surface of theocean, having initial parameters as at a point 50, is pumped to arequired higher pressure by a water or third pump P3 to form thepressurized cold seawater stream S51 as described above. The pressurizedcold seawater stream S51 is then sent into the sixth heat exchange unitHE6, where it cools or absorbs thermal energy from the intermediatesolution stream S22 in the sixth heat exchange process 22-23 or 51-52 asdescribed see above to form the warmed pressurized cold seawater streamS52 having parameters as at the point 52.

Thereafter, the warmed pressurized cold seawater stream S52 passesthrough a first heat exchange unit HE1, providing cooling to orabsorbing thermal energy from the rich solution stream S26 in the heatexchange process 26-1 or 52-53 as described above to form the spent coldseawater stream S53 having parameters as at a point 53. The spent streamS53 is then discharged from the subsystem 108 into the cold seawateroutlet system 128.

As follows from this description, the cold seawater used as coolant inthe condensers HE6 (sixth heat exchange unit) and HE1 (first heatexchange unit) is used consecutively, i.e., the cold seawater streamexiting the condenser HE6 is forwarded to the condenser HE1. Theconsecutive use of the cold seawater stream S50 in both condensers HE6and HE1 allows a drastic reduction in the required flow rate of thecooling water per unit of power produced.

The subsystem 108 utilizes a number of streams having differentcompositions of the lower boiling component(s) and the higher boilingcomponent(s) of a single multi-component working fluid. Streams having ahigher concentration of the lower boiling component(s) are referred toas “rich” streams, while streams having a lower concentration of thelower boiling component(s) or a higher concentration of the higherboiling component(s) are referred to as “lean” streams. Table Itabulates the different streams and the points corresponding to thestreams as well as indicating the richness or leanness of eachcomposition. Two rich vapor streams are list first in general order ofrichness, with no concern for which is richer just that they are bothricher than the rich solution stream. In a similar manner, the two leanliquid streams produced by the two separating units are ranked as theleanest stream, but one is not ranked leaner than the other as theimportant thing is the both streams are leaner then the intermediatesolution and the lean solution.

TABLE I Compositions (Rich or Lean) of the Multi-Component Working Fluidfor SLT-4b Streams Points Richness/Leanness S16, S17 and S18 16, 17 and18 first rich vapor S15 15 second rich vapor S26, S1, S2, S3, and S8 26,1, 2, 3 and 8 rich solution S22, S23, S24, S25, S9, 22, 23, 24, 25, 9,6, 5 intermediate solution S6, S5 and S7 and 7 S14 14 lean solution S11and S19 11 and 19 first lean liquid S20, S10 and S21 20, 10, and 21second lean liquid

Comparing the subsystem 108 of this invention with applicable systems inthe prior art, e.g., assorted Rankine cycles, the present subsystem 108provides a substantial increase in power output per unit of flow rate ofcooling water. In addition, the present system also provides asubstantial reduction in the use of warm seawater per unit of powergenerated.

The present systems and method are not intended to maximize efficiency,but to maximum power production per unit of cold seawater as the coldseawater must be produced from deep in the ocean or sea, while the warmseawater supply is unlimited. Because the warm seawater supply islimitless and the cold seawater supply is limited, the circulation ofwarm seawater through the heat exchanger units HE2, HE3 and HE4 may beincreased reducing the size of these heat exchanger units.

The performance of the present subsystem 108, in comparison to the priorart (a Rankine Cycle using a pure ammonia working fluid) is given inTable II, below.

TABLE II Flow Rates and Net Output and Net Output Increase Cold SeawaterWarm Seawater Flow Rate Flow Rate Net Output Net Output System(lb./hour) (lb./hour) (kW) Increase^(†) Rankine 66,666,022 110,000,0007,605   +0% Cycle (baseline) SLT-4a 66,666,022 108,002,645 11,760 +54.6%Rankine Cycle is baseline.

New Disclosure

In the system designated SLT-4 b of FIG. 2, the composition of the richsolution stream S26 having the parameters as at the point 26 wasattained by mixing the rich vapor stream S15 having the parameters as atthe point 15 coming from the separator SP2 and the intermediate solutionliquid stream S25 having the parameters as at the point 25.

In the case that the temperature of the stream S1 drops to a SLT-4 c-dtemperature, where the SLT-4 c-d temperature is characterized when theliquid stream S11 derived from the stream S1 is richer than theintermediate solution stream S25, the an improved result may be achievedif the rich solution stream S26 is formed by mixing the rich vaporstream S15 and a pressure adjusted, first liquid substream S25 derivedfrom the liquid stream S11 exiting the first separator SP1. The use of aportion of the liquid stream S11 to mix with the rich vapor stream S15produces two new variants of the OTEC system of this inventiondesignated SLT-4 c and SLT-4 d. SLT-4 c is set forth pictorially in FIG.3 and SLT-4 d is set forth pictorially in FIG. 4.

In SLT-4 c, the liquid stream S11 is divided into a first substream S12having parameters as at a point 12 and a second substream S13 havingparameters as at a point 13. The first substream S12 contains a majorityof the flow of the liquid stream S11, where the majority means an amountgreater then 50% of the flow of the stream S11 leaving the firstseparator SP1.

The first substream S12 is then throttled in the throttle valve TV1,reducing its pressure to the pressure the rich vapor stream S15 havingthe parameters at the point 15 to form a stream S25 having parameters asat a 25.

The stream S25 is then mixed with the rich vapor stream S15 exiting fromthe second separator SP2 to form the rich solution stream S26 having theparameters as at the point 26.

Because the stream S25 is richer than the intermediate solution streamS23 having the parameters as at the point 23, the formation of thestream S26 requires a smaller quantity of rich vapor, i.e., the flow ofthe rich vapor stream S15 may be reduced. This allows a composition ofthe stream S23 to be leaner than in the system designated SLT-4 b ofFIG. 2, which in turn, lowers a pressure of the stream S23 having theparameters as at the point 23 and affords a corresponding reduction in apressure of the spent stream S18 having the parameters as at the point18. This reduction in the pressure of the spent stream S18 increases anexpansion ratio, and an output of the turbine T1.

Meanwhile, the second substream 513 comprising the remaining, minorportion (less than 50% of the flow) of the stream S11 is throttled in afourth throttle valve TV4, where its pressure is reduced to form astream 513′ having parameters as at a point 13′. The stream 513′ is thenmixed with the liquid S20 to form a stream S20′ having the parameters asat a point 20′, which is then cooled in the fifth heat exchange unit HE5to form the stream S10 having the parameters as at the point 10.

From this point forward, the system SLT-4 c of FIG. 3 operates asdescribed for SLT-4 b pictorially illustrated of FIG. 2.

The OTEC system designated SLT-4 d of FIG. 4 shows an alternativearrangement with even better results. In SLT-4 d, the stream 513′ ismixed with the intermediate solution stream S6 exiting from fifth heatexchange unit HE5 to form a slightly enriched, intermediate solutionstream S6′ having parameters as at a point 6′.

The stream S6′ is then forwarded to the fourth heat exchange unit HE4for partial vaporization. From this point forward, the system SLT-4 doperates as described above for SLT-4 c and SLT-4 b.

TABLE III Compositions (Rich or Lean) of the Multi-Component WorkingFluid for SLT-4c Richness/ Streams Points Leanness S16, S17 and S18 16,17 and 18 first rich vapor S15 15 second rich vapor S26, S1, S2, S3, andS8 26, 1, 2, 3 and 8 rich solution S22, S23, S24, S9, S6, 22, 23, 24, 9,6, 5 intermediate S5 and S7 and 7 solution S11, S12, S25, S13, and S13′11, 12, 25, 13 and 13′ first lean liquid S20, S10 and S21 20, 10, and 21second lean liquid S20′ 20′ mixed lean liquid

TABLE IV Compositions (Rich or Lean) of the Multi-Component WorkingFluid for SLT-4d Richness/ Streams Points Leanness S16, S17 and S18 16,17 and 18 first rich vapor S15 15 second rich vapor S26, S1, S2, S3, andS8 26, 1, 2, 3 and 8 rich solution S6′ 6′ enriched intermediate solutionS22, S23, S24, S25, S9, 22, 23, 24, 25, 9, 6, 5 intermediate S6, S5 andS7 and 7 solution S11, S12, S25, S13, and S13′ 11, 12, 25, 13 and 13′first lean liquid S20, S10 and S21 20, 10, and 21 second lean liquid

Both variants of the systems shown above provide an increase in the netoutput of the system. SLT-4 c gives an increase in output ofapproximately 5.25% as compared to SLT-4 b, while SLT-4 d gives anincrease in output of approximately 5.37% as compared to SLT-4 b.

All references cited herein are incorporated by reference. Although theinvention has been disclosed with reference to various embodiments,those of skill in the art may appreciate changes and modification thatmay be made which do not depart from the scope and spirit of thisinvention.

1. A system for generating electrical and/or mechanical energycomprising: a vessel or a floating platform, a warm seawater supplysubsystem comprising a collector, piping and a warm seawater pump (P4),where the warm seawater supply subsystem collects warm seawater from anocean or a sea and pressurized it to form a higher pressure warmseawater stream, a warm seawater discharge subsystem for dischargingspent warm seawater back into the ocean or sea, a cold seawater supplysubsystem comprising a collector, piping and a cold seawater pump (P3),where the cold seawater supply subsystem collects cold seawater from adepth up to two miles below a surface of the ocean or sea, a coldseawater discharge subsystem for discharging spent cold seawater backinto the ocean or sea, and a thermal energy conversion subsystemincluding: a turbine or energy converting subsystem for converting aportion of thermal energy in a first rich vapor stream into a useableform of energy to from a spent stream, a condensing subsystem including:a first condenser for condensing an intermediate solution streamcomprising the spent stream and a cooled second lean liquid streamutilizing a higher pressure, cold seawater stream to form a fullycondensed, intermediate solution stream, a first pump for pressurizingthe fully condensed intermediate solution stream to a higher pressure, afirst dividing valve for dividing the higher pressure, fully condensed,intermediate solution stream into a first higher pressure, fullycondensed, intermediate solution substream and a higher pressure, fullycondensed, intermediate solution second substream, a second condenserfor condensing a rich solution stream comprising the first fullycondensed, higher pressure intermediate solution substream and a secondrich vapor stream and a second pump for pressurizing the fullycondensed, rich solution stream to a higher pressure, a preheatingsubsystem including: a first pre-heater or pre-heating heat exchangeunit for preheating the second fully condensed, higher pressure,intermediate solution substream with thermal energy from a second leanliquid stream and a second pre-heater or pre-heating heat exchange unitfor preheating the higher pressure, fully condensed, rich solutionstream with thermal energy from a first cooled warm seawater substream,a partial vaporizing subsystem including: a first partial vaporizingheat exchange unit for partially vaporizing the preheated, higherpressure, intermediate solution stream with thermal energy from a secondcooled warm seawater substream and for partially vaporizing thepreheated, higher pressure, rich solution stream with thermal energyfrom a higher pressure warm seawater stream, and a separating subsystemincluding: a first separator for separating the partially vaporized,higher pressure, intermediate solution stream into the first rich vaporstream and a first lean liquid stream and a second separator forseparating a lean stream comprising the first lean liquid stream and thepartially vaporized, higher pressure, intermediate solution stream intothe second rich vapor stream and a second lean liquid stream, where allof the streams are derived from a multi-component working fluid and thethermal energy conversion subsystem is closed with respect to themulti-component working fluid.
 2. The system of claim 1, wherein thewarm seawater supply subsystem collector collects warm seawater from ator with in 10 meters of the surface of the ocean or sea, where the warmseawater has a temperature between about 20° C. and about 30° C.
 3. Thesystem of claim 1, wherein all of the streams are derived from themulti-component working fluid, wherein all of the higher pressures arethe same or different, wherein the rich vapor streams are richer thanthe rich solution streams, which is richer than the intermediatestreams, which is richer than then lean solution stream, and which isricher than the lean liquid streams.
 4. The system of claim 1, wherein atemperature differential between the warm seawater and the cold seawateris between about 15° C. and about 30° C.
 5. The system of claim 1,wherein the useable form of energy is electrical and/or mechanicalenergy.
 6. The system of claim 1, wherein the cold seawater supplysubsystem collector collects cold seawater from a depth between about0.5 and 1.5 miles below the surface of the ocean or sea having atemperature between about 1° C. and about 10° C.
 7. The system of claim1, wherein the multi-component working fluid comprises one or aplurality of lower boiling point components, lower boiling components,and one or a plurality of higher boiling point components, higherboiling components.
 8. The system of claim 1, wherein themulti-component working an ammonia-water mixture, a mixture of two ormore hydrocarbons, a mixture of two or more freon, a mixture ofhydrocarbons and freon.
 9. The system of claim 1, wherein themulti-component working fluid a mixture of water and ammonia.
 10. Thesystem of claim 1, wherein a net relative output compared to a Rankinecycle using pure ammonia is increased by at least about 20%.
 11. Thesystem of claim 1, wherein a net relative output compared to a Rankinecycle using pure ammonia is increased by at least about 25%.
 12. Thesystem of claim 1, wherein a net relative output compared to a Rankinecycle using pure ammonia is increased by at least about 30%.
 13. Thesystem of claim 1, wherein a net relative output compared to a Rankinecycle using pure ammonia is increased by at least about 35%.
 14. Thesystem of claim 1, wherein a net relative output compared to a Rankinecycle using pure ammonia is increased by at least about 40%.
 15. Thesystem of claim 1, wherein a net relative output compared to a Rankinecycle using pure ammonia is increased by at least about 45%.
 16. Thesystem of claim 1, wherein a net relative output compared to a Rankinecycle using pure ammonia is increased by at least about 50%.
 17. Thesystem of claim 1, wherein a net relative output compared to a Rankinecycle using pure ammonia is increased by at least about 55%.
 18. Athermal energy conversion system comprising: a turbine or energyconverting subsystem for converting a portion of thermal energy in afirst rich vapor stream into a useable form of energy to from a spentstream, a condensing subsystem including: a first condenser forcondensing an intermediate solution stream comprising the spent streamand a cooled second lean liquid stream utilizing a higher pressure, coldseawater stream to form a fully condensed, intermediate solution stream,a first pump for pressurizing the fully condensed intermediate solutionstream to a higher pressure, a first dividing valve for dividing thehigher pressure, fully condensed, intermediate solution stream into afirst higher pressure, fully condensed, intermediate solution substreamand a higher pressure, fully condensed, intermediate solution secondsubstream, a second condenser for condensing a rich solution streamcomprising the first fully condensed, higher pressure intermediatesolution substream and a second rich vapor stream and a second pump forpressurizing the fully condensed, rich solution stream to a higherpressure, a preheating subsystem including: a first pre-heater orpre-heating heat exchange unit for preheating the second fullycondensed, higher pressure, intermediate solution substream with thermalenergy from a second lean liquid stream and a second pre-heater orpre-heating heat exchange unit for preheating the higher pressure, fullycondensed, rich solution stream with thermal energy from a first cooledwarm seawater substream, a partial vaporizing subsystem including: afirst partial vaporizing heat exchange unit for partially vaporizing thepreheated, higher pressure, intermediate solution stream with thermalenergy from a second cooled warm seawater substream and for partiallyvaporizing the preheated, higher pressure, rich solution stream withthermal energy from a higher pressure warm seawater stream, and aseparating subsystem including: a first separator for separating thepartially vaporized, higher pressure, intermediate solution stream intothe first rich vapor stream and a first lean liquid stream and a secondseparator for separating a lean stream comprising the first lean liquidstream and the partially vaporized, higher pressure, intermediatesolution stream into the second rich vapor stream and a second leanliquid stream, where all of the streams are derived from amulti-component working fluid and the system is closed with respect tothe multi-component working fluid.
 19. The system of claim 18, whereinthe turbine or energy converting subsystem comprises a single stageturbine or a multi-stage turbine.
 20. The system of claim 18, whereinthe condensing subsystem comprises: a first condenser (HE6) forcondensing the intermediate solution stream comprising the spent richsolution stream and the cooled second lean liquid stream utilizing thehigher pressure, cold seawater stream, a first pump (P2) forpressurizing the fully condensed intermediate solution stream to ahigher pressure, a first dividing valve for dividing the higherpressure, fully condensed, intermediate solution stream into the firstsubstream and the second substream, a second condenser (HE1) forcondensing the rich solution stream comprising the first fullycondensed, higher pressure intermediate solution substream and thesecond rich vapor stream, and a second pump (P1) for pressurizing thefully condensed, rich solution stream to a higher pressure.
 21. Thesystem of claim 18, wherein the preheating subsystem comprises: a firstpreheater (HE5) for preheating the second fully condensed, higherpressure, intermediate solution substream with thermal energy from thesecond lean liquid stream and a second preheater (HE2) for preheatingthe higher pressure, fully condensed, rich solution stream with thermalenergy from the first cooled warm seawater substream,
 22. The system ofclaim 18, wherein the partial vaporizing subsystem comprises: a firstpartial vaporizer (HE4) for partially vaporizing the preheated, higherpressure, intermediate solution stream with thermal energy from thesecond cooled warm seawater substream and a second partial vaporizer(HE2) for partially vaporizing the preheated, higher pressure, richsolution stream with thermal energy from the higher pressure warmseawater stream.
 23. The system of claim 18, wherein the separatingsubsystem comprising: a first separator (SP2) for separating thepartially vaporized, higher pressure, intermediate solution stream intothe first rich vapor stream and the first lean liquid stream and asecond separator (SP1) for separating a lean stream comprising the firstlean liquid stream and the partially vaporized, higher pressure,intermediate solution stream into the second rich vapor stream and thesecond lean liquid stream.
 24. The system of claim 18, wherein the warmseawater supply subsystem collector collects warm seawater from at orwith in 10 meters of the surface of the ocean or sea, where the warmseawater has a temperature between about 20° C. and about 30° C.
 25. Thesystem of claim 18, wherein all of the streams are derived from themulti-component working fluid, wherein all of the higher pressures arethe same or different, wherein the rich vapor streams are richer thanthe rich solution streams, which is richer than the intermediatestreams, which is richer than then lean solution stream, and which isricher than the lean liquid streams.
 26. The system of claim 18, whereina temperature differential between the warm seawater and the coldseawater is between about 15° C. and about 30° C.
 27. The system ofclaim 18, wherein the useable form of energy is electrical and/ormechanical energy.
 28. The system of claim 18, wherein the cold seawatersupply subsystem collector collects cold seawater from a depth betweenabout 0.5 and 1.5 miles below the surface of the ocean or sea having atemperature between about 1° C. and about 10° C.
 29. The system of claim18, wherein the multi-component working fluid comprises one or aplurality of lower boiling point components, lower boiling components,and one or a plurality of higher boiling point components, higherboiling components.
 30. The system of claim 18, wherein themulti-component working an ammonia-water mixture, a mixture of two ormore hydrocarbons, a mixture of two or more freon, a mixture ofhydrocarbons and freon.
 31. The system of claim 18, wherein themulti-component working fluid a mixture of water and ammonia.
 32. Amethod for producing electrical and/or mechanical energy from atemperature different between warm surface seawater and cold seawatercollected at depths up to 2 miles below the surface of an ocean or sea,where the method comprises: passing a first rich vapor stream, which maybe pressure adjusted in a third throttle control valve if needed,through a turbine unit, where a portion of thermal energy in the firstrich vapor stream is converted to a useable form of energy to produce aspent rich solution stream, combining the spent rich solution streamwith a cooled second lean liquid stream, which may be pressure adjustedin a third throttle control valve if needed, to form an intermediatesolution stream, where the intermediate solution stream is leaner thanthe rich solution stream, condensing the intermediate solution stream ina first condenser utilizing a cold seawater stream to form a fullycondensed, intermediate solution stream to form a warmed cold seawaterstream, pressurizing the fully condensed intermediate solution stream ina first pump to a higher pressure to form a higher pressure, fullycondensed intermediate stream, dividing the higher pressure, fullycondensed intermediate stream into a first higher pressure, fullycondensed intermediate substream and a second higher pressure, fullycondensed intermediate substream, combining the first higher pressure,fully condensed intermediate substream with a second rich vapor streamto form a rich solution stream, condensing the rich solution stream in asecond condenser utilizing the warmed cold seawater stream to form afully condensed rich solution stream, pressurizing the fully condensedrich solution stream in a second pump to a higher pressure to form ahigher pressure, fully condensed rich solution stream, preheating thehigher pressure, fully condensed rich solution stream in a firstpreheater utilizing a first cooled warm seawater substream to form apreheated, higher pressure, rich solution stream, partially vaporizingthe preheated higher pressure, rich solution stream in a first partialvaporizer unit to from a partially vaporized, rich solution stream and acooled warm seawater stream, dividing the cooled warm seawater streaminto the first cooled warm seawater substream and a second cooled warmseawater substream, separating the partially vaporized, rich solutionstream in a first separator to form the first rich vapor stream and afirst lean liquid stream, meanwhile, preheating the second higherpressure, fully condensed, intermediate substream in a second preheaterutilizing the second lean liquid stream to form a preheated, secondhigher pressure, intermediate substream and the cooled second leanliquid stream, partially vaporizing the preheated, second higherpressure, intermediate substream in a second partial vaporizer unitutilizing the second cooled warm seawater substream to form a partiallyvaporized, second higher pressure, intermediate substream, combining thepartially vaporized, second higher pressure, intermediate substream withthe first lean liquid stream, which may be pressure adjusted by a firstthrottle control valve if needed, to form a lean solution stream, andseparating the lean solution stream in a second separator to form thesecond rich vapor stream and the second lean liquid stream, where thesystem is closed with respect to the multi-component working fluid.